Intermittent web feed mechanism providing low velocity feed prior to stoppage



March 20, 1962 M. SORKIN INTERMITTENT WEB FEED MECHANISM PROVIDING LOW VELOCITY FEED PRIOR TO STOPPAGE Flled. Oct 25, 1957 pm 0e 5 0 N m5 9 V m N5 Mr /0 & A

United States Patent 'Ofiiice 3,025,740 Patented Mar. 20, 1962 York Filed Oct. 23, 1957, Ser. No. 691,856 6 Claims. (Cl. 83282) This invention relates to intermittent web feed mechanisms, and more particularly to a photo-electrically timed web clamp to improve the accuracy of such mechanism.

There are many processes in which it is necessary to feed a web continuously at one place, and intermittently at another. A common example is the combination of a rotary printing press with a reciprocating press which scores, creases, punches or cuts a printed web. For brevity the term punch is used hereinafter for all such operations. The punch press works on an intermittently stationary web, which forms part of a web which is moving at constant velocity in the printing press. The problem is to secure accurate registration of the print and the cut, combined with high speed operation.

Mechanism for intermittent feed through a punch press is disclosed in US. Patent No. 2,658,406 entitled Variable Speed Feed Mechanism granted November 10, 1953 to John Gibson McIlvain, Jr. A different mechanism for the same purpose is disclosed in US. Patent No. 2,548,136 entitled Register Control Means for Continuous and Intermittent Web Feed Mechanism granted April 10, 1951 to Frederick Auer.

These mechanisms cause acceleration to a speed substantially higher than the average web speed, and deceleration down to Zero velocity or dwell of the web. The mechanism usually provides a period of uniform high velocity between accleration and deceleration, in order to help compensate for the dwell period without requiring too high a maximum velocity.

It has proved difficult to obtain perfect cutto-print register. It has been found that backlash is a major factor in causing cut-to-print variations, because of the intermittent drive, which repeatedly accelerates and decelerates. The error caused by this factor tends to grow worse as the parts of the mechanism become worn. It has already been suggested to load the intermittent feed roller by means of a brake, thus keeping the backlash in one direction at all times. This is helpful, but is inetficient because of the substantial waste of power and excessive wear of the mechanism caused by the continuous application of braking force. It has also been suggested to use a clamp or brake which is applied directly to a fast moving web in order to stop the same, but such clamps have not proved desirable because they may injure the web, and in any event with the web moving at high velocity the desired degree of accuracy is not obtained.

The prime object of the present invention is to generally improve intermittent feed mechanisms of the variable speed type. A more particular object is to change the variable speed cycle of the web to provide a brief interval of low uniform velocity just before the dwell period, and to combine the said modified variable speed drive with a web clamp which positively stops the web at exactly the desired instant during the aforesaid brief interval of low velocity movement. The variable speed drive may be controlled mechanically in the usual way, but the clamp is preferably independently controlled by electronic means including a photo electric eye or scanner which responds to the actual printing on the web, and preferably at a point at or close to the punch press, thereby insuring accuracy of cut-to-print registry.

To accomplish the foregoing general objects, and other more specific objects which will hereinafter appear, my invention resides in the intermittent web feed mechanism, and the elements thereof, and their relation one to another, as are hereinafter more particularly described in the following specification. The specification is accompanied by drawings in which:

FIG. 1 is a side elevation drawn to small scale showing apparatus utilizing the present invention;

FIG. 2 is a fragmentary section explanatory of one form of variable speed drive which may be used as a part of the present invention;

FIG. 3 is a'diagram explanatory of the invention; and

FIG. 4 is a graph explanatory of a feature of the invention'.

Referring to the drawing, and more particularly to FIGS. land 3, the entire line of machinery may be driven by a main drive shaft 12, which extends lengthwise of the moving web 20. Shaft 12 may be driven in any desired fashion, as by means of a main driving motor 14 (FIG. 3), operating through appropriate belts, chains or gearing indicated at 16.

The web 20 may be acted on by a series of multicolor printing units, which may be of the gravure type. The last two of a series of such units are here shown at 22 and 24 in FIG. 1. Each has a gravure cylinder 26 (FIG. 3) driven by main shaft 12 through gearing indicated at 28. The printing units may be conventional, and may include the usual driers at 23 and 27 (FIG. 1) to dry the web between successive printing operations. Elaborate mechanism, including electric eye scanners 30 (FIG. 1), may be provided between successive printing units to maintain the different colors in registration, and for this purpose, the gearing symbolized at 28 (FIG. 3) may include an appropriate running register, preferably of the planetary or differential gear type, which permits the automatic feed of a slight positive or negative motion from correction motors to maintain registration. Scanning mechanism for this purpose may be of the type shown 'in my US. Patent 2,348,862 entitled Register Control Apparatus, issued on May 16, 1944. Running register mechanism is shown in US. Patent 2,163,035 entitled Apparatus for Eifecting Register of Multiple Operations issued June 20, 1939 to William F. Grupe.

The printed web is fed to a punch press 32 by means of an intermittent feed roller 34, cooperating as usual with an idler 36. The press 32 is driven by main shaft 12 through appropriate gearing at 38 and 40, connected at 42, and serving to reciprocate the punch, as by means of connecting rods 44 leading to eccentrics on punch press shaft 46. The intermittent feed roller 34 is also driven from main shaft 12, as by means of gearing in box 48 and box 50, the latter including appropriate cam or like mechanism to convert the continuous uniform speed rotation of shaft 12 to an intermittent rotation of roller 34. This mechanism may be of any suitable type, including for example the-Mcllvain drive shown in Patent 2,658,- 406, or the Auer drive shown in Patent 2,548,136, previously mentioned.

The intermittent drive as heretofore designed would produce a web movement of the character shown graphically in solid lines in FIG. 4 of the drawing. This graph plots the web velocity as a function of angular rotation, for one full cycle of the punch press. The average web speed at the printing cylinder 26, where the speed is uniform, is indicated by the horizontal broken line 52. The web speed produced by the feed roller varies between a high velocity shown at 54, and a dwell or zero velocity shown at 56. The reciprocating punch operates on the web during the dwell period at 56 The deceleration of the web from maximum to zero velocity is shown at 58. The acceleration of the web from zero to maximum velocity is shown at 60. Of course, the cycle used in any particular intermittent feed mechanism may differ, but in all cases, it is essential to have a dwell or zero velocity period during which a reciprocating press may operate on the web, and it is necessary to accelerate to a high velocity to make up for the dwell period. It is necessary to decelerate in order to provide the dwell period. The symmetrical curve 60, 54, 58, 56 shown in FIG. 4 is a simple and desirable way to achieve the intended purpose, but it is not essential that the deceleration and acceleration be at the same rate, nor is it essential to have a period of uniform high velocity, as shown at 54. The latter is desired in order to lessen the needed maximum velocity to obtain the required average velocity 52. Also the graph is idealized in that the corners usually would not be sharp as here shown.

Regardless of the particular nature of the intermittent feed mechanism, it is evident that because of the alternating acceleration and deceleration, any backlash or play in all of the parts of the mechanism will introduce some uncertainty or inaccuracy in the feed. Many things have been done in an effort to improve the cut-to-print registration. For example, reverting to FIG. 3, the apparatus includes a web pull unit using a pull roller 62 which is driven from the main drive shaft 12 through a gear box 64. Pull roller 62 cooperates with an idler 66. A slack loop of web is provided at 6% between the uniform velocity pull roller 62 and the intermittent feed roller 34. During each cycle this loop grows, say to the dotted line position 68, during dwell at roller 34, and then the loop is taken up and reduced to minim-um dimension. This latter position of the loop may be determined by a fixed cylinder 70. The gear ratio in the drive 48 leading to intermittent feed roller 34 is preferably so selected that the web is momentarily pulled tight once during each cycle. At that time, tension builds up between the intermittent feed roller 34 and the pull cylinder 62, as determined by the position of the stop cylinder 70, and the web then slips at the intermittent feed roller 34. As the intermittent feed roller 34 decelerates, and its peripheral speed approaches the speed of the web feeding out of the pull roller 62, the slipping stops and the web coming out of the feed roller 34 is controlled by that roller.

To correct or maintain the register, a compensator roller 72 may be interposed between the last printing unit and the pull roller 62. The vertical position of compensator 72 may be controlled by a correction motor 74, driving vertical screws 76 which raise or lower the compensator roller 72. This may be under control of a web scanner 78 located near the pull roller 62, and cooperating with a suitable phase detector mounted on or geared to the main drive shaft 12. The phase detector may be of the type described in my aforesaid Patent 2,348,862.

The pull roller 62 is normally so selected that its peripheral speed very slightly exceeds that of the printing cylinder 26, and therefore the web is under tension therebetween. For perfect cut-to-print register, the position of a target printed on the web should remain in a fixed phase relationship with the printing cylinders as the web passes the pull roller 62. If a slack loop is brought to a stop, as shown at 70, the print should be in fixed phase relationship to the printing press cylinder 26 at the instant that the web stops slipping at the intermittent feed roller 34. All of this apparatus has been used before, and may be retained now along with my improvement, but is less important now and may be made to less accurate standards now.

For perfect cut-to-print register, it would also be necessary for the web to travel precisely the same distance during each cycle from that instant until it is stopped under the die. The various gear boxes, such as 48 and 64 include change gears to accommodate changes in the length of the sheet or print, so that it will not be necessary to change the diameter of the rollers 34 and 62 for each different print length. There is lost motion in all such gearing. The backlash in the intermittent drive mechanism 50 itself contributes to cut-to-print variation. Loading the intermittent feed roller 34 by means of a brake might be helpful, but obviously is inefficient and wasteful of power, and hastens wear of the mechanism.

Referring now to FIG. 3, in accordance with my invention the apparatus additionally includes a photoelectric cell 170 controlled by the previous operation on the web, in this case the printing on the web. There is also circuitry indicated at associated with the photoelectric cell 170 for precision web control by means of clamps. For this purpose, there is a clamp 176 located adjacent the punch press 32, and arranged to momentarily clamp the web in order to positively stop it. A companion clamp 178 may be provided ahead of feed roll 34. An additional means, generally designated 80, together with circuitry 75, controls the timing of the operation of the clamp means, in order to maintain the punch press operation in registration with the printing on the web.

For release of the clamp bars, appropriate means may be provided, and in this case, I provide a microswitch 172 which is controlled by the position of an element, in this case a cam 174, which moves with the apparatus performing the operation on the web, that is, with the punch press 32.

Referring now to FIG. 2, the variable feed mechanism there shown is of the type disclosed in the aforesaid McIlvain Patent 2,658,406 and it includes a cam 82. The shape of the cam as heretofore-designed produced acceleration, uniform high velocity, deceleration, and dwell, as shown in solid lines in FIG. 4, and as previously described. However, in the present case the shape of the cam is modified, particularly in the region 84, to produce a brief interval of uniform low velocity immediately preceeding the dwell period.

This is illustrated by the graph shown in dotted lines in FIG. 4 of the drawing. The modified graph is characterized by acceleration 86 and uniform high velocity 88, much as before. These are followed by a deceleration 90, which however, is discontinued when a very low velocity is reached, and the low velocity is maintained for a brief interval, as is indicated at 92. Thereafter the web is again decelerated, as shown at 94, the small amount needed to bring it to the zero velocity shown at 56. To distinguish the momentary final deceleration 94, from the main deceleration 90, I shall refer to the part 94 as stoppage, in which case my new cycle comprises acceleration, uniform high velocity, deceleration, uniform low velocity, stoppage, and dwell.

The high velocity 88 is slightly greater than velocity 54 to compensate for the loss between deceleration 58 and 90. It will be understood that the interval 92 of uniform low velocity is suitably located to straddle the desired clamp instant for precise registration. Thus the clamp 176 will stop the web during this low velocity movement, and is able to positively stop the web accurately for the desired registration. The clamp is released before renewed acceleration begins. The timing for release of the clamp can be taken from one of the shafts, most simply the punch press shaft 46. However, the timing for descent of the clamp is taken from a marker on the web cooperating with the web scanner 170, which is preferably located as near as possible to the press.

Reverting to FIG. 2 and considering the variable speed drive in greater detail, the power input is at pinion 96, meshing with a gear 98, which revolves the pivot of a planet gear 102, meshing with a sun gear 104. Inasmuch as planet gear 102 turns only a fraction of a revolution on the said pivot 109, the planet may be mutilated, leaving only a sector of a gear, as shown. The sector 102 is affixed to an arm 106 oscillatable about pivot 160. Arm 106 carries a cam follower roller 108 which is received in the cam groove 82 previously referred to. The cam and its groove are stationary.

The output is applied by sun gear 104 to a shaft 110 which leads to a bevel gear 112 meshing with a bevel pinion 114 which in turn drives a shaft 116 leading to bevel gear 118 meshing with bevel gear 120. The latter turns the feed roller 34 previously referred to.

Reverting now to FIG. 3 of the drawing, the web scanner 170 is preferably located just ahead of and as close as feasible to the punch press 32. The clamp 176 also is preferably close to the punch press. It is not necessary to have two clamp bars, but it is preferred to employ the two bars 176, 178, one on each side of thefeed roll 34, in order to help maintain a more positive control of the web.

The clamps 176, 178 are operated by hydraulic cylinders 126, 128, which are energized from a suitable source 130 of hydraulic power. The hydraulic fluid is controlled by a solenoid operated valve shown at 80, and the latter is controlled by circuitry housed at 75.

The circuitry is not illustrated in detail, and may assume a variety of forms. Essentially the passage of a mark on the web beneath the eye 170 may be used through conventional circuitry to trip the operation of the clamp, and for appropriate corrective adjustment one may shift the location of the mark on the web, or shift the location of the scanner 170 longitudinally of the web, or vary the time delay between the scanner impulse and the actual clamp action.

Considerably improved cut-to-print register is possible using my new method. It may be said that in this method the frame of the punch is itself used as a reference for the proper location of the print.

The web scanner 170 is located on the punch infeed in position to view the register mark on the web just as it approaches its correct position with respect to the die in the punch. At that time it triggers the clamping mechanism, which stops the web by applying a force between clamping bars 176, 178 and the fixed structure supporting the web directly beneath the bars. In my system, the intermittent web motion is so modified that the web is travelling at low speed (approximately to of average web speed) when the clamp is applied to the web. Thus, any error in cut-to-print register caused by variations in the clamping time and clamping conditions is proportionately reduced.

By using two clamps, one before and one after the intermittent feed roller, the web is held absolutely stationary at the time the die comes in contact with the web, so that the intermittent drive during this time is prevented from moving the web. The slow speed section of the intermittent drive cycle is designed to provide at least A" of web travel, so that variations in the infeed mechanism fall within this slow speed travel section. Thus the accuracy of cut-to-print depends only upon thereliability of the web scanner triggering the clamp, and the accuracy of repetition of the clamping motion.

The release of the clamps may be timed quite roughly, compared to their clamping action. The reason is that once the die reaches the Web, the web is held by the die itself, until the die rises and releases the web. The

clamps may be released any time after the die engages the web, and before acceleration begins. For this purpose, I provide a cam 174 on the press shaft 46, operating a microswitch 172 connected to the circuitry in box 75. This changes the valve solenoid at 80, and so raises the clamps 176, 178.

Other methods may be used, for example, an adjustable time interval. However, it is better to relate the release to the punch press position, thus making it independent of shaft and web speed, including starting up, and slowing to a stop.

In FIG. 3 the stop roll 70 is still present, and functions usefully during rough setting up of preliminary registration, but during actual operation the web'loop 68-does not reach and actually hit the stop roll 70, and there preferably is a slight slack, as is indicated on the drawing.

The clamp mechanism must accurately repeat its motion once each punch cycle, and stop the web in minimum time after the triggering impulse from the scanner, in order to minimize changes of cut-to-print register with changing speed. For example, if the web is travelling at 1200 feet per minute or 240 inches per second at full web speed, it will travel 0.240 inch per millisecond. With my modified intermittent motion shown in the graph (FIG. 4) at speed the web will travel 0.024 inch; at speed 0.012 inch; and at V speed 0.008 inch. The following table relates the clamping time and speed ratio to web travel per millisecond at various web speeds from 6 00 ft./min. to 1200 ft./min.

Table I Web Speed in Fit/Min.

Web Travel in inches per From this table it is possible to pick a suitable set of values for the maximum time of operation of the clamping mechanism, and permissible variation in the clamping time, for any desired accuracy of cut-to-print register.

The illustrated mechanism consisting of an electrohydraulic valve controlling a hydraulic cylinder which actuates the clamping linkage, can achieve the rapid action required. If the distance the clamping bars travel is 0.020 inch, and if oil at 700 lbs. per sq. inch pressure is available at a rate of 2.4 gallons per min., feeding a hydraulic cylinder with /2 sq. in. plunger area, the clamping action takes place in approximately 3 milliseconds. Allowing for web thickness variation of 0.002 inch the clamping time may vary 0.3 milliseconds. The clamping force per bar is approximately lbs. From Table I, at 1200 ft./min. and speed, register variation would be 0.0036 inch. Position change from crawl speed to 1200 ft./min. would be 0.036 inch.

It is believed that the construction and operation as well as the advantages of my improved intermittent web feed mechanism will be apparent from the foregoing detailed description. The rough or approximate control of the web is obtained by means of a variable speed feed mechanism. This is so designed as to introduce a brief interval of very low velocity movement of the web ahead of the more usual dwell period. During the low velocity travel an additional positive clamp means is accurately triggered to positively stop the web. Its control is efiicient and accurate because of the slow speed of the web at the time it is clamped. The timing of the clamp is independently controlled by electronic circuitry, including a web scanner which is responsive to the actual printing on the web, and thus the web may be positively stopped in proper position for accurate registry of cut-toprint.

It will be apparent that while I have shown and described my invention in a preferred form, changes may be made in the structure shown without departing from the scope of the invention as sought to be defined in the following claims. In the claims the term stoppage is used for the part 94 of the cycle shown in FIG. 4, as above defined.

I claim:

1. Apparatus for feeding a moving web through web treating apparatus which operates on the web when stationary and for causing said operation to be in proper registration with a previous operation on the web, said apparatus comprising an intermittent web feed mechanism to move the web through the apparatus intermittently, said intermittent web feed mechanism comprising a feed roll, a drive shaft which rotates at uniform velocity and which is connected to and which thereby rotates in synchronism with the web treating apparatus, mechanism between said drive shaft and said feed roll to rotate the latter intermittently, said mechanism including a cam driven by said drive shaft and associated parts driven by said cam to cause rotation of the feed roll in a variable speed cycle, the shape of said cam being such that the cycle produced by rotation of the cam includes acceleration, deceleration, uniform low velocity, stoppage and dwell, a triggering means controlled by the previous operation on the web, clamp means adjacent the apparatus and adapted to momentarily clamp the web during its aforesaid uniform low velocity movement in order to positively stop it, and means whereby said triggering means controls the timing of the operation of said clamp means in order to maintain the apparatus operation in registration with the previous operation on the web.

2. Apparatus for feeding a moving printed web through a punch press which operates on the web when stationary and for causing said operation to be in proper registration with the printing on the web, said apparatus comprising an intermittent web feed mechanism to move the web through the punch press intermittently, said intermittent web feed mechanism comprising a feed roll, a drive shaft which rotates at uniform velocity and which is connected to and thereby rotates in synchronism with the punch press, mechanism between said drive shaft and said feed roll to rotate the latter intermittently, said mechanism including a cam driven by said drive shaft and associated parts driven by said cam to cause rotation of the feed roll in a variable speed cycle, the shape of said cam being such that the cycle produced by rotation of the cam includes acceleration, deceleration, uniform low velocity, stoppage and dwell, a photoelectric cell controlled by the printing on the web, circuitry associated with said photoelectric cell, clamp means adjacent the punch press and adapted to momentarily clamp the web during its low velocity movement in order to positively stop it, means whereby said circuitry controls the timing of the operation of said clamp means in order to maintain the punch press operation in registration with the printing on the web, and means to release the clamp means.

3. Apparatus for feeding a moving printed web through a punch press which operates on the web when stationary and for causing said operation to be in proper registration with the printing on the web, said apparatus comprising a uniform velocity drive shaft to drive the punch press, an intermittent web feed mechanism driven by said shaft to move the web through the punch press intermittently, said intermittent web feed mechanism comprising a feed roll, mechanism between said drive shaft and said feed roll to rotate the latter intermittently, said mechanism including a cam driven by said drive shaft and associated parts driven by said cam to cause rotation of the feed roll in a variable speed cycle, the shape of said cam being such that the cycle produced by rotation of the cam includes acceleration, uniform high velocity, deceleration, uniform low velocity, stoppage and dwell, a photoelectric cell controlled by the printing on the web, circuitry associated with said photoelectric cell, clamp means adjacent the punch press and adapted to momentarily clamp the web during its low velocity movement in order to positively stop it, means whereby said circuitry controls the timing of the operation of said clamp means in order to maintain the punch press operation in registration with the printing on the web, and means driven by said shaft to time the release of the clamp means.

4. Apparatus for feeding a moving Web through web treating apparatus which operates on the web when stationary and for causing said operation to be in proper registration with a previous operation on the web, said apparatus comprising an intermittent web feed mechanism to move the web through the apparatus intermittently, said intermittent web feed mechanism comprising a feed roll, a drive shaft which rotates at uniform velocity and which is connected to and which thereby rotates in synchronism with the Web treating apparatus, mechanism between said drive shaft and said feed roll to rotate the latter intermittently, said mechanism including a cam driven by said drive shaft and associated parts driven by said cam to cause rotation of the feed roll in a variable speed cycle, the shape of said cam being such that the cycle produced by rotation of the cam includes acceleration, uniform high velocity, deceleration, uniform low velocity, stoppage and dwell, a triggering means controlled by the previous operation on the Web, clamp means adjacent the apparatus and adapted to momentarily clamp the web during its aforesaid uniform low velocity movement in order to positively stop it, and means whereby said triggering means controls the timing of the operation of said clamp means in order to maintain the apparatus operation in registration with the previous operation on the web.

5. Apparatus for feeding a moving web of paper or like light weight material which is received at uniform high speed, through web treating apparatus which operates on the web when stationary and for causing said operation to be in proper registration with a previous operation on the web, said apparatus comprising an intermittent web feed mechanism to move the web through the apparatus intermittently in uniform increments, said intermittent web feed mechanism comprising a feed roll, a drive shaft which rotates at uniform velocity and which is connected to and which thereby rotates in synchronism with the web treating apparatus, mechanism between said drive shaft and said feed roll to rotate the latter intermittently, said mechanism including a cam driven by said drive shaft and associated parts driven by said cam to cause rotation of the feed roll in a variable speed cycle, said cam being driven by said drive shaft at a speed of the order of hundreds of revolutions per minute, the shape of said cam being such that the cycle produced by rotation of the cam includes acceleration, uniform high velocity, deceleration, uniform low velocity, stoppage and dwell, the period of uniform low Velocity being very brief compared to the length of the cycle, a triggering means controlled-by the previous operation on the web, clamp means adjacent the apparatus and adapted to momentarily clamp the web during its aforesaid uniform low velocity movement in order to positively stop it, and means whereby said triggering means controls the timing of the operation of said clamp means in order to maintain the apparatus operation in registration with the previous operation on the web.

6. Apparatus for feeding a moving printed web of paper or like light weight material which is received at uniform high speed, through a punch press which operates on the web when stationary and for causing said operation to be in proper registration with the printing on the web, said apparatus comprising a uniform velocity drive shaft to drive the punch press, and intermittent web feed mechanism driven by said shaft to move the web through the punch press intermittently in uniform increments, said intermittent Web feed mechanism comprising a feed roll, mechanism between said drive shaft and said feed roll to rotate the latter intermittently, said mechanism including a cam driven by said drive shaft and associated parts driven by said cam to cause rotation of the feed roll in a variable speed cycle, said cam being driven by said drive shaft at a speed of the order of hundreds of revolutions per minute, the shape of said cam being such that the cycle produced by rotation of the cam includes acceleration, uniform high velocity, deceleration, uniform low velocity, stoppage and dwell, the period of uniform low velocity being very brief compared to the length of the cycle, a photoelectric cell controlled by the printing on the web, circuitry associated with said photoelectric cell, clamp means adjacent the punch press and adapted to momentarily clamp the web during its low velocity movement in order to positively stop it, means whereby said circuitry controls the timing of the operation of said clamp means in order to maintain the punch press operation in registration with the printing on the web, and means driven by said shaft to time the release of the clamp means.

1,435,979 Reed Nov. 21, 1922 10 Rose Mar. 20, Grupe Iune 20, Williamson Jan. 6,

Sorkin May 16, Auer Apr. 10, Secrest Jan. 8,

McIlvain Nov. 10,

Fletcher Apr. 27, Cornell June 10,

Funnell Aug. 11, 

